Purely classicial electromagnetically induced transparency in metamaterials

Electromagnetically induced transparency is normally a quantum mechanical effect observed in the interaction of light with certain three-level atomic systems. Due to this process, a narrow transparency window with low absorption can be observed in the middle of a broader absorption peak. Here we show that a similar effect can be observed in metamaterials, i.e., in artificially constructed materials containing small electromagnetic resonators as their "atomic" elements. We achieve the electromagnetically induced transparency with the use of two linearly coupled resonators such as finite-wire and split-ring resonators.
First, we explain how the effect can be achieved due to the destructive interference in the normal modes of a coupled system of purely classical resonators. Subsequently, we present the absorption spectra of the metamaterial and the retrieved material parameters (permittivity and permeability). Finally, we show that the group velocity of light can be reduced considerably due to the steep dispersion associated with the dark resonance in the transmission window, which could be beneficial for slow-light applications.